Absorbent articles comprising wetness indicators

ABSTRACT

An absorbent article of the present invention may comprise a backsheet and a wetness indicator composition. The wetness indicator composition may comprise a stabilizer, a colorant, and a matrix. And, a wetness indicator sample, according to the Wetness Indicator Sample Test (Phosphate), may have a phosphate content of 10% or less. Further, the wetness indicator sample, according to the Wetness Indicator Sample Test (Nitrogen), may have a nitrogen content of 3% or less.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/168,762, filed Apr. 13, 2009, the substance of which is incorporatedherein by reference.

FIELD OF THE INVENTION

This invention is directed to wetness indicators comprising wetnessindicator compositions. Particularly, wetness indication compositionshaving improved colorant stability.

BACKGROUND OF THE INVENTION

Many disposable absorbent articles comprise a wetness indicatorcomposition. Wetness indicator compositions may comprise a colorantadapted to change in appearance, i.e., appear, disappear, change color,etc., upon contact with liquids such as, urine, runny bowel movements,menses, etc., in the article. Wetness indicating compositions describedherein are of the substantially insoluble type such that they aredesigned so the composition generally remains in the same location ofthe article before and after being wetted with liquid. Some wetnessindicator compositions are intentionally designed to simply disappearinto the core of the diaper after being wetted (e.g., wetted withurine). Wetness indicator compositions of the present invention mayfunction to serve the following: 1) the wetness indicator compositionshould effectively adhere, but not substantially bleed through, to thesubstrate on which it is applied (e.g., the backsheet) and shouldpossess an optimum balance of cohesive strength and flexibility toremain intact during storage, as well as upon and after being wetted, 2)the initial color of the wetness indicator composition should notprematurely change color such that it confuses the caregiver or weareras to whether a wetness event has occurred, 3) the color change of thewetness indicator composition should occur as quickly as possible afterthe wetness event, 4) the contrast in colors between the dry and wettedstates of the wetness indicator composition should be great enough tosignal the occurrence of the wetness event, 5) the color signaling thewetness event should remain visible for a long period of time after thewetness event and should not migrate to other regions of the diaper suchthat the signal denoting the wetness event becomes difficult orimpossible to interpret, 6) the wetness indicators of the presentinvention should adhere, but not substantially bleed through, to thesubstrate that it comes in direct contact with (e.g., the nonwovendusting layer) or that it is in close proximity to (e.g., the corecover) to provide for adequate wicking of fluid (e.g., urine), 7) thewetness indicator composition should remain stable (i.e., not changecolor prior to a wetness event) when placed in close proximity (if notdirect contact) with higher (versus the colorant of the wetnessindicator composition) pH absorbent article components, and 8) thewetness indicator composition should be easily made, easily processedfor application onto the wearable article, be safe, and of economicalcost.

While problems realized in the past (including high humidity andtemperature environments) remain, there are additional challengesassociated with new diaper designs, particularly including diaperdesigns comprising absorbent cores that are substantially cellulosefree. These core designs comprise increased levels of absorbent polymermaterial, adhesives (including, thermoplastic adhesive materials), andsurfactants. Each of these comprise chemical compositions that can alterthe pH of the wetness indicator composition and thus cause a colorchange prior to a wetness event. Particularly, alkaline surfactantscontaining amine, amide, or quaternary functionalities are especiallyproblematic for wetness indicator compositions comprising colorants thatchange color as the pH rises; but even lower pH moieties likecarboxylates can also pose challenges and prematurely activate certaincolorants within such wetness indicator compositions.

The color changing active used in many wetness indicator compositionsare pH indicators like bromocresol green which changes color from yellowto blue in the pH range of 3.8 to 5.4. To maintain the yellow color ofthe bromocresol green in the dry state, the wetness indicatorcomposition should be acidic enough to keep it in its yellow state. Fora wetness indicator composition containing the bromocresol green pHindicator, it remains yellow up to the point urine contacts it andthereafter turns blue due to the pH increase. In diapers incorporating awetness indicator composition comprising a colorant that changes coloras its pH increases, it is common practice for one to incorporate acids(as well as other chemical components discussed in more detail below)within the wetness indicator composition to maintain the yellow colorstate of pH indicators, like bromocresol green, prior to a wetnessevent.

In diaper designs, placing the wetness indicator composition in closeproximity to absorbent cores that are substantially cellulose free orcomprising high levels of surfactants, there is a desire to optimize theacid content in relation to other materials present in the wetnessindicator composition to aid in preventing its premature color change.This is especially true when the diaper design utilizes lower basisweight and more breathable substrates (e.g., backsheets, dusting layers,and core covers) because these substrates allow pH altering chemicals tocome in closer proximity with the wetness indicator composition. But,while the acid content is optimized for stability, one also needs tooptimize the wetness indicator composition for proper functioning of theother properties (e.g., kinetics, dye retention, stability, adhesion,etc.). If too much acid or too strong of an acid mixture isincorporated, the pH can remain suppressed even after the wetness eventsuch that the yellow color of the bromocresol green, for instance,persists and no blue color (signaling a wetness event) results even whena wetness event has occurred. If too little acid or too weak of an acidmixture is incorporated, the wetness indicator composition canprematurely change color. Thus, the acid content should be optimized sothe wetness indicator composition remains stable under various storagescenarios, as well as within new challenging absorbent article designs.

Beyond these stability issues, the wetness indicator composition shouldadhere to the substrate (e.g., the dusting layer) it faces that isinboard of the wetness indicator to ensure wicking of fluid (e.g.,urine) to the wetness indicator composition after a wetness event. Thatis, when a gap exists between the wetness indicator composition and theinboard substrate (e.g., the dusting layer) that it faces, fluid may nottravel from the absorbent core to the wetness indicator within thedesired time to signal a wetness event. It may additionally be desiredthat there is substantial contact/adherence to the substrate it faces toensure that the wetness indicator composition is evenly (top to bottomand side to side) wetted and thus provides the full signal intended.This can be accomplished by providing a wetness indicator compositionthat has an optimized “open time” such it is tacky enough, during itsincorporation into an absorbent article, for a long enough time toadhere to the substrate, but not so long that it bleeds through thesubstrate.

Overall, there remains a need for a wetness indicator composition thatis stable in the presence of challenging diaper designs, particularlythose designs comprising: absorbent cores that are substantiallycellulose free and comprising high levels of adhesive (including,thermoplastic adhesive material) and absorbent polymer material, lowerbasis weight dusting layers and backsheets, and dusting layers and/orcore covers coated with surfactants. Particularly, there is a need formore acidic wetness indicator compositions that comprise lessphosphorous and/or nitrogen (which correlates to greater colorantstability while still providing acceptable color changing kinetics andretention). Additionally, there is a need for a wetness indicatorcomposition that has an optimized “open time” for use in absorbentarticles comprising lower basis weight and breathable films andnonwovens.

SUMMARY OF THE INVENTION

An absorbent article of the present invention may comprise a backsheetand a wetness indicator composition. The wetness indicator compositionmay comprise a stabilizer, a colorant, and a matrix. And, a wetnessindicator sample, according to the Wetness Indicator Sample Test(Phosphate), may have a phosphate content of 10% or less.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial longitudinal cross sectional view of an absorbentcore (comprising a nonwoven layer and a complex of absorbent polymermaterial and thermoplastic adhesive material) in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

It should be understood that every limit given throughout thisspecification will include every lower, or higher limit, as the case maybe, as if such lower or higher limit was expressly written herein. Everyrange given throughout this specification will include every narrowerrange that falls within such broader range, as if such narrower rangeswere all expressly written herein.

All percentages, ratios and proportions are by weight, and alltemperatures are in degrees Celsius (° C.), unless otherwise specified.All measurements are in SI units unless otherwise specified.

“Absorbent article” refers to devices that absorb and contain bodyexudates, and, more specifically, refers to devices that are placedagainst or in proximity to the body of the wearer to absorb and containthe various exudates discharged from the body. Absorbent articles mayinclude diapers, training pants, adult incontinence undergarments,feminine hygiene products, breast pads, care mats, bibs, wound dressingproducts, and the like. As used herein, the term “body fluids” or “bodyexudates” includes, but is not limited to, urine, blood, vaginaldischarges, breast milk, sweat and fecal matter.

“Absorbent core” means a structure typically disposed between a topsheetand backsheet of an absorbent article for absorbing and containingliquid received by the absorbent article and may comprise one or moresubstrates, absorbent polymer material disposed on the one or moresubstrates, and a thermoplastic composition on the absorbent particulatepolymer material and at least a portion of the one or more substratesfor immobilizing the absorbent particulate polymer material on the oneor more substrates. In a multilayer absorbent core, the absorbent coremay also include a cover layer. The one or more substrates and the coverlayer may comprise a nonwoven. Further, the absorbent core issubstantially cellulose free. The absorbent core does not include anacquisition system, a topsheet, or a backsheet of the absorbent article.In a certain embodiment, the absorbent core would consist essentially ofthe one or more substrates, the absorbent polymer material, thethermoplastic composition, and optionally the cover layer. Absorbentcores that may be used in the present invention are disclosed in US Pub.Nos. 2004/0162536 to Becker filed on Feb. 11, 2004; 2007/0167928 toBecker filed on Mar. 13, 2007; 2007/0179464 to Becker filed on Mar. 13,2007; 2007/0156108 to Becker filed on Mar. 13, 2007; and 2004/0167486 toBusam filed on Feb. 11, 2004; U.S. Ser. Nos. 60/936,102 to Hundorf filedon Jun. 18, 2007; 60/936,109 to Hundorf filed on Jun. 18, 2007;60/936,149 to Hundorf filed on Jun. 18, 2007; 60/936,085 to Ashton filedon Jun. 18, 2007; 60/936,084 to Ashton filed on Jun. 18, 2007;60/936,150 to Ashton filed on Jun. 18, 2007; 60/936,146 to Ashton filedon Jun. 18, 2007; 60/936,037 to Ashton filed on Jun. 18, 2007; and61/091,799 to Hundorf filed on Aug. 26, 2008.

“Absorbent polymer material,” “absorbent gelling material,” “AGM,”“superabsorbent,” and “superabsorbent material” are used hereininterchangeably and refer to cross linked polymeric materials that canabsorb at least 5 times their weight of an aqueous 0.9% saline solutionas measured using the Centrifuge Retention Capacity test (Edana441.2-01).

“Airfelt” is used herein to refer to comminuted wood pulp, which is aform of cellulosic fiber.

“Comprise,” “comprising,” and “comprises” are open ended terms, eachspecifies the presence of what follows, e.g., a component, but does notpreclude the presence of other features, e.g., elements, steps,components known in the art, or disclosed herein.

“Consisting essentially of” is used herein to limit the scope of subjectmatter, such as that in a claim, to the specified materials or steps andthose that do not materially affect the basic and novel characteristicsof the subject matter.

“Diaper” refers to an absorbent article generally worn by infants andincontinent persons about the lower torso so as to encircle the waistand legs of the wearer and that is specifically adapted to receive andcontain urinary and fecal waste. As used herein, term “diaper” alsoincludes “pants” which is defined below.

“Fiber” and “filament” are used interchangeably.

A “nonwoven” is a manufactured sheet, web, or batt of directionally orrandomly orientated fibers, bonded by friction, and/or cohesion and/oradhesion, excluding paper and products which are woven, knitted, tufted,stitch-bonded incorporating binding yarns or filaments, or felted bywet-milling, whether or not additionally needled. The fibers may be ofnatural or man-made origin and may be staple or continuous filaments orbe formed in situ. Commercially available fibers have diameters rangingfrom less than about 0.001 mm to more than about 0.2 mm and they come inseveral different forms: short fibers (known as staple, or chopped),continuous single fibers (filaments or monofilaments), untwisted bundlesof continuous filaments (tow), and twisted bundles of continuousfilaments (yarn). Nonwoven fabrics can be formed by many processes suchas meltblowing, spunbonding, solvent spinning, electrospinning, andcarding. The basis weight of nonwoven fabrics is usually expressed ingrams per square meter (gsm).

“Pant” or “training pant”, as used herein, refer to disposable garmentshaving a waist opening and leg openings designed for infant or adultwearers. A pant may be placed in position on the wearer by inserting thewearer's legs into the leg openings and sliding the pant into positionabout a wearer's lower torso. A pant may be preformed by any suitabletechnique including, but not limited to, joining together portions ofthe article using refastenable and/or non-refastenable bonds (e.g.,seam, weld, adhesive, cohesive bond, fastener, etc.). A pant may bepreformed anywhere along the circumference of the article (e.g., sidefastened, front waist fastened). While the terms “pant” or “pants” areused herein, pants are also commonly referred to as “closed diapers,”“prefastened diapers,” “pull-on diapers,” “training pants,” and“diaper-pants.” Suitable pants are disclosed in U.S. Pat. No. 5,246,433,issued to Hasse, et al. on Sep. 21, 1993; U.S. Pat. No. 5,569,234,issued to Buell et al. on Oct. 29, 1996; U.S. Pat. No. 6,120,487, issuedto Ashton on Sep. 19, 2000; U.S. Pat. No. 6,120,489, issued to Johnsonet al. on Sep. 19, 2000; U.S. Pat. No. 4,940,464, issued to Van Gompelet al. on Jul. 10, 1990; U.S. Pat. No. 5,092,861, issued to Nomura etal. on Mar. 3, 1992; U.S. Patent Publication No. 2003/0233082 A1,entitled “Highly Flexible And Low Deformation Fastening Device”, filedon Jun. 13, 2002; U.S. Pat. No. 5,897,545, issued to Kline et al. onApr. 27, 1999; U.S. Pat. No. 5,957,908, issued to Kline et al on Sep.28, 1999; and U.S. Ser. Nos. 11/197,197 to LaVon et al filed Aug. 4,2005; 11/224,462 to LaVon et al filed on Sep. 12, 2005; 11/286,614 toLaVon on Nov. 23, 2005; 11/286,612 to LaVon on Nov. 23, 2005; and11/709,500 issued to LaVon et al on Feb. 27, 2007.

“Substantially cellulose free” is used herein to describe an articlecomponent, such as an absorbent core, that contains less than 10% byweight cellulosic fibers, less than 5% cellulosic fibers, less than 1%cellulosic fibers, no cellulosic fibers, or no more than an immaterialamount of cellulosic fibers. An immaterial amount of cellulosic materialwould not materially affect the thinness, flexibility, or absorbency ofan absorbent core. Substantially cellulose free absorbent cores 10 maycomprise absorbent polymer material 16 adhered to the dusting layer(e.g., 12) via thermoplastic adhesive material 18 forming a “complex”14. The complex 14 may be in rows 20 (see FIG. 1).

“Substantially surfactant free” is used herein to describe an articlecomponent, such as a dusting layer, that contains less than 10% byweight of a surfactant or mixture thereof, less than 5% by weight ofsurfactant, less than 1% by weight of surfactant, no surfactant, or nomore than an immaterial amount of surfactant where the surfactant may beanionic, cationic, nonionic, amphoteric or may include mixtures thereofand function to increase the wettability of the article component byreducing the contact angle of synthetic urine (as disclosed in U.S. Pat.No. 6,772,708 to Klofta) in contact with the surface of the articlecomponent (e.g., fibers of a nonwoven material or the surface of afilm).

“Thermoplastic adhesive material” as used herein is understood tocomprise a polymer composition from which fibers are formed and appliedto the superabsorbent material with the intent to immobilize thesuperabsorbent material in both the dry and/or wet state. Thethermoplastic adhesive material of the present invention forms a fibrousnetwork over the superabsorbent material. Thermoplastic adhesivematerial may comprise one or a mixture of adhesives, including, but notlimited to polymers such as polybutylene, copolymers such as styrenicblock copolymers, tackifying resins, synthetic rubbers like those of thestyrene butadiene and carboxylated styrene butadiene types, naturalrubbers, waxes such as paraffin and microcrystalline waxes, oils such asmineral oil, anti-oxidants, and the like as is known in the art.

Wetness Indicator Composition

Wetness indicators of the present invention may comprise a wetnessindicator composition. The wetness indicator compositions of the presentinvention comprise a colorant, a matrix, and additional ingredients, allof which are illustrated in more detail herein. Furthermore, the wetnessindicator compositions of the present invention may optionally beattached to a substrate, such as, a structural component of a absorbentarticle. Substrates, disposable absorbent articles and structuralcomponents thereof are illustrated in more detail herein.

(a) Colorant

The wetness indicator compositions of the present invention may comprisea colorant. The colorant has an initial color state, which is associatedwith a first state of the wetness indicator composition. Examples ofthis first color state include, but are not limited to, colors visibleto the human eye, such as, red, blue, green, indigo, violet, yellow,orange, purple, and the like; colors not visible to the human eye, suchas, colors visible in the ultra violet (or UV), or infra red (or IR)portion of the electromagnetic spectrum, and the like. The first colorstate may be invisible, white, black, translucent or opaque. Thecolorant(s) also has a final color state, which is associated with asecond state of the wetness indicator composition. Examples of thissecond color state include, but are not limited to, colors visible tothe human eye, such as, red, blue, green, indigo, violet, yellow,orange, purple, and the like; colors not visible to the human eye, suchas, colors visible in the UV, or IR portion of the electromagneticspectrum, and the like. The second color state may be invisible, white,black, translucent, opaque, or have a change in intensity or visualdistinctiveness, and the like, when compared to the first color state.The initial color state of the colorant is different, in some form, tothe final color state. For example, the initial color state may be afirst color, such as, yellow, while the second color state may be adifferent color, such as blue; or the initial color state may be a firstcolor, such as, blue, while the second color state may be transparent,such as, a color not visible to the human eye, and only visible in theUV portion of the electromagnetic spectrum.

In the wetness indicator compositions of the present invention, theinitial color state is associated with a first state of the wetnessindicator composition. This first state of the wetness indicatorcomposition includes, but is not limited to: a specific pH or pH range;absence or presence of a specific compound or compounds, such as, water,urea, dissolved oxygen, ions, such as, but not limited to, iron,calcium, magnesium, zinc, sodium, chloride, protons, hydroxide andcombinations thereof, sugars, such as, glucose, enzymes, biologicalmaterials in the urine and/or feces; and combinations thereof;microbiological flora and fauna, such as, bacteria and the like; somethreshold level of a compound or composition, such as, water, urine etc,below a certain amount; and combinations thereof.

In the wetness indicator compositions of the present invention the finalcolor state is associated with a second state of the wetness indicatorcomposition. This second state of the wetness indicator compositionincludes, but is not limited to: a specific pH or pH range; absence orpresence of a specific compound or compounds, such as, water, urea,dissolved oxygen, ions, such as, but not limited to, iron, calcium,magnesium, zinc, sodium, chloride, protons, hydroxide and combinationsthereof, sugars, such as, glucose, enzymes, biological materials in theurine and/or feces; and combinations thereof; microbiological flora andfauna, such as, bacteria and the like; some threshold level of acompound or composition, such as, water, urine, menses, blood and thelike; and combinations thereof.

In one embodiment of the present invention, the first state is aspecific pH or pH range and the second state is a specific pH or pHrange different to the specific pH or pH range of the first state. Inone optional embodiment of the present invention the second state is thepH or pH range of urine, preferably human urine, as measured as a neatsolution at human body temperature (typically 37.6° C.). The pH or pHrange of urine is typically about 5.5 to about 8.0. In this optionalembodiment, the first state may be a specific pH or pH range which ismore acidic or more basic than the second state, that is, a pH of lessthan about 5.5 or greater than about 8.0. In one optional embodiment ofthe present invention, the colorant is a pH indicator. Non-limitingexamples of suitable pH indicators include those disclosed in U.S. Pat.No. 6,904,865 to Klofta.

In one optional embodiment of the present invention, the colorant is asulfonephthalein pH indicator, such as, but not limited to, bromocresolgreen, bromocresol purple, m-cresol purple, cresol red, chlorophenolred, bromothymol blue, bromopyrogallol red, bromoxylenol blue,bromophenol blue, and combinations thereof. In an acidic state, thesulfonephthalein class of indicators are most commonly yellow in color.Upon contact with liquid, such as urine, having a pH higher than theirpK_(a), the sulfonephthalein class of pH indicators typically change toa green, blue or purple color.

In another optional embodiment of the present invention, the wetnessindicator composition may comprise of two or more colorants, each havingat least one of their first and second states different, i.e., differentpK_(a) values, a pH and an enzyme trigger, a pH trigger, etc., colors,solubilities, or other properties. The varying first and second statesmay facilitate interactive scenes, sequences, or displays providinginformation regarding relative fullness/wetness of the article or merelyprovide entertainment and/or aesthetic value. For example, the wetnessindicating composition may contain one colorant that turns blue andanother that turns red upon contact with urine. Alternatively, oneportion of the graphic may appear and another portion may disappear uponcontact with liquid, such as urine, menses, blood, and the like.Finally, one might include a small quantity of an oil soluble dye likeD&C red or D&C yellow to change both the initial and final states of thecolor for a sulfonephthalein type of pH indicator like bromocresolgreen. This can lead to color changing combinations which can be moreaesthetically pleasing to caregivers.

In another optional embodiment of the present invention the wetnessindicator composition may comprise two or more colorants, each havingtheir first and second state the same.

The colorant may be employed in compositions at levels which areeffective at indicating the presence of a liquid, and include from about0.001% to about 5%, from about 0.005% to about 2%, and from about 0.01%to about 1%, and even from 0.01% to 0.5% by weight of the composition.

(b) Matrix

The compositions of the present invention may comprise a matrixcomprising first and second binding agents, both of which areillustrated in more detail herein. The matrix acts to hold the colorantin place before, during and after contact with liquid. The matrix of thepresent invention may be highly resistant to colorant leaching, and maybe resistant to premature activation in high humidity environments. Uponcontact with liquid, such as urine, menses, blood or the like, thematrix allows sufficient liquid to contact the colorant and effect achange in appearance. The matrix concurrently aids in inhibiting thecolorant, in either its initial color state or final color state, fromleaching out of the matrix into the surrounding environment, such as,the absorbent core of a disposable absorbent article.

When the wetness indicating composition is attached to a substrate, thematrix and consequently the composition, should have sufficient wet anddry cohesion, adhesion, and/or flexibility to remain fully retained onthe substrate. In other words, the composition retains sufficientflexibility, cohesion, and adhesion to prevent portions of thecomposition from separating, such as, portions of the compositionchipping off or flaking off from the rest of the composition and/or thesubstrate. Thus, the matrix aids in not only preserving and inhibitingthe leaching of the colorant, but it also aids in maintaining thestructural integrity of the wetness indicator composition in both thedry and wet states.

The matrix, including both the first and second binding agents, may beemployed in wetness indicator compositions at levels which are effectiveat immobilizing and stabilizing the colorant, including from about 5% toabout 95%, from about 10% to about 80%, and from about 25% to about 75%,by weight of the composition.

(i) First Binding Agent

The first binding agent may be any material which immobilizes thecolorant when the colorant is in its initial color state. There arevarious materials which may be suitable for use as the first bindingagent for the wetness indicating compositions of the present invention.The material selected as the first binding agent will be any materialwhich immobilizes the colorant when in its first color state. In oneembodiment of the present invention, possible first binding agentsinclude, but are not limited to, rosins, rosin esters, polymerizedrosins, pentaerythritol rosin esters, styrenated terpenes, polyterpeneresins, terpene phenolics, and combinations thereof.

A suitable rosin mixture is the combination of Arizona Chemical'sSylvatac RE98 and Sylvaros PR-295. The Sylvatac RE-98 is apentaerythritol rosin ester and the Sylvaros PR-295 is a polymerizedrosin. Both are economical matrix ingredients, both contribute to adarker color in the dry state, both aid in maintaining effectivecohesive and adhesive forces, and their acidic nature helps preserve thecolorant in its dry state color. In addition to being a suitable firstbinding agent, rosin esters, polymerized rosins, and pentaerythritolrosin esters may also be a effective solubilizers for some of the otheringredients in these wetness indicating compositions. Furthermore, whilenot wishing to be limited by theory and as noted, the acidity of somerosin esters, polymerized rosins and pentaerythritol rosin esters isbelieved to contribute to the stabilization of particular colorants,such as, but not limited to, pH indicators. For example, some of theserosins contain acidic carboxylate groups which aid in keeping a colorantlike bromocresol green in its acidic yellow state. This acidic yellowstate is the preferred color for the dry state of the wetness indicatorcomposition when a pH indicator like bromocresol green is incorporatedinto the composition.

The first binding material immobilizes the colorant when in its initialcolor state. How the first binding material immobilizes to the colorantwhen in its initial color state depends upon both what the first bindingmaterial and colorant are. For example, the first binding agentimmobilizes the colorant when the colorant is in its initial color stateby one or more forces selected from the group consisting of adhesion,hydrogen bonding, ionic, polar covalent bonding, Van der Waals forces,dipole-dipole forces, London dispersion forces and combinations thereof.

The first binding agent may be employed in compositions at levels whichare effective at immobilizing and stabilizing the colorant in its firststate, including from about 4% to about 90%, from about 10% to about75%, and from about 20% to about 65%, by weight of the composition.

(ii) Second Binding Agent

The second binding agent may be any material which immobilizes thecolorant when the colorant is in its final color state. There arevarious materials which may be suitable for use as the second bindingagent for the wetness indicating compositions of the present invention.

In one embodiment of the present invention the second binding agents maybe selected from, but are not limited to those second binding agentsdisclosed in U.S. Pat. No. 6,904,865 to Klofta.

In one optional embodiment of the present invention the second bindingagent is selected from the group consisting of quaternary ammonium saltcompounds, cationic clay, polyacrylic acid polymers, organic acids, andcombinations thereof. Examples of suitable quaternary ammonium compoundsinclude, but are not limited to,dimethyl(2-ethylhexylhydrogenatedtallowalkyl) ammonium methyl sulfate,cocoalkylmethyl[ethoxylated(15)] ammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethyl ammonium methyl sulfate,octadecyltrimethyl ammonium chloride, dicocoalkyldimethly ammoniumchloride, di(hydrogenated tallowalkyl)dimethyl ammonium chloride, anddistearyldimethyl ammonium chloride.

It should be noted that the counter anion associated with the quaternarycompound, or any second binding agent having one or more cationic group,is not specifically limited to chloride. Other anions can also beemployed and non-limiting examples include methyl sulfate and nitrite.Similarly, any suitable counter cation, such as, but not limited to,sodium, potassium, calcium, magnesium, zinc, protons, ammonium,substituted ammonium and the like, may be associated with a secondbinding agent having one or more anionic groups.

The second binding material immobilizes the colorant when in its finalcolor state. How the second binding material immobilizes the colorantwhen in its final color state depends upon the chemical composition ofboth the second binding material and colorant. For example, if thecolorant's final color state is that of an anionic long chain moleculeand the second binding material is a cationic molecule, then the bondformed may be, for example, an ionic bond, a covalent bond, or the like.Another example, if the colorant's final color state is that of acationic molecule, and the second binding material is an anionic longchain molecule, then the bond formed may be, for example, an ionic bond,covalent bond, or the like.

In one embodiment of the present invention the second binding agentimmobilizes the colorant when the colorant is in its final color stateby one or more selected from the group consisting of covalent bonding,ionic bonding, Van der Waals, and combinations thereof.

Without wishing to be bound by theory, it is believed that when thecolorant is an anion in its final color state and the second bindingagent is a cation or the colorant is a cation in its final color stateand the second binding agent is an anion, the second binding agent formsan ionically bonded coacervate with the colorant. For example, when thefinal state associated with a colorant's final color state is the pH ofurine, contacting the colorant with urine will change the colorant toits final color state, i.e. an anion, and this forms an ionic bond withthe second binding agent, which is a cation. The coacervate formation isdue to the strong coulombic interaction between the opposite charges ofthe colorant and the second binding agent. The coacervate formed betweenthe colorant and the second binding agent neutralizes the charge in bothspecies and dramatically reduces both of their solubilities in polarsolvents such as water or urine while the coacervate's solubility in thematrix remains high due to this charge neutralization and thecoacervate's more lipophilic nature. Both of these effects dramaticallyinhibits the leaching of the colorant from the matrix. The increasedlipophilicity of the coacervate leads to increased intermolecularbonding forces between the coacervate and components of the matrix.These intermolecular forces may further limit the diffusion and mobilityof the colorant into an aqueous environment such as urine.

In certain optional embodiments of the present invention, use ofcationic quaternary ammonium compounds as the second binding agent mayalso function to darken or intensify the color change of certaincolorants, especially those belonging to the sulfonephthalein class ofpH indicators. Without wishing to be bound by theory, it is believedthis darkening is due to several possible factors: 1) alkalineimpurities within the quaternary ammonium raw material, 2) absorptionshifting and absorptivity coefficient increases due to coacervateformation and/or 3) increased formation of the colorant in its finalcolor state.

The second binding agent may be employed in compositions at levels whichare effective at immobilizing the colorant in its second state,including from about 0.5% to about 20%, from about 0.5% to about 10%,and from about 0.1% to about 5%, by weight of the composition.

Stabilizer Ingredient

Wetness indicator compositions of the present invention may include astabilizer. It may be desirable to include a stabilizer when thecolorant is a pH indicator and when the absorbent article could bestored under conditions of high humidities and temperatures. Theinclusion of a stabilizer within the wetness indicator composition isalso especially important for new diaper designs where materials and/orchemicals are present that could potentially prematurely activate thecolor change of the colorant within the wetness indicator composition.

In one embodiment of the present invention, the stabilizer is an acidicstabilizer. In another embodiment of the present invention, thestabilizer is a basic stabilizer. The inclusion of a stabilizer, whilenot wishing to be limited by theory, is believed to play a role instabilizing the colorant against premature changes caused by exposure tohumid environments and/or certain components of the diaper, bymaintaining a stable pH, such as a low pH environment with an acidicstabilizer, around the colorant even when the system is exposed to highhumidities and/or certain components of the diaper. This maintenance ofa stable pH environment keeps the colorant, especially when the colorantis a pH indicator, in its initial dry color state.

One of the key properties of a properly functioning wetness indicator isfor it to maintain its dry state color during a variety of storage andpackaging conditions while still undergoing a noticeable color change ina reasonable amount of time after being contacted by urine. The colorantshould also remain stable to various chemicals and materials that mightbe present in the diaper. Although acidic moieties present in the rosinsas part of the matrix can aid in preserving the dry state color,additional stabilizer ingredients have been found to be necessary withsome new diaper designs where high pH components within the diaper cancause the undesirable and premature color change activation of thecolorant. To maintain the colorant in its acidic dry state color, acidsof suitable strength should be added. Suitable strength is defined bythe colorant and pH range where it changes color.

For a pH indicator colorant like the sulfonephthalein class whichincludes bromocresol green which changes color between a pH of 3.8 and5.4 (See “The Sigma-Aldrich Handbook of Stains, Dyes and Indicators,” byFloyd J. Green, Aldrich Chemical Co., Milwaukee, Wis.), the stabilizershould contribute suitably strong acidic moieties to keep thebromocresol green in its yellow state within the matrix. Although manystrong acids like sulfuric acid and hydrochloric acid have suitably lowpH's to accomplish this, their solubilities are low in these anhydrousmatrices. In addition, their high acidity can chemically decompose thestructures of some of the components present in the wetness compositionand diaper. As noted, carboxylic acid moieties present in the matrixingredients like rosins can also aid in maintaining the colorant in itsacidic color state but carboxylic acids are typically too weak tomaintain the dry yellow state of bromocresol green if it is exposed tohigh humidities and/or high pH components within new diaper designs. Toincrease the strength of the carboxylic acids, one can add electronwithdrawing groups between the carboxylic acid moiety and anotherportion of the molecule. Although a fatty acid like stearic acid can aidin preserving the dry state color, it can be made more effective bymaking it a stronger acid by inserting polyoxyethylene groups betweenthe carboxylic acid group and the alkyl chain. These types of moleculesare called ether carboxylates and these acidic molecules can beeffective in maintaining the dry state acid form of the pH indicatorcolorant like bromocresol green. In addition, the alkyl group present inthese ether carboxylates increases their solubility in the wetnessindicator matrix. Finally, the ether carboxylate's surfactancy can aidin increasing the kinetics for activating the color change of thewetness indicator composition after it is contacted by urine.

Other suitable stabilizers are those of the monoalkyl phosphate freeacid and dialkyl phosphate free acid types. The phosphate acid moiety isa stronger acid than the carboxylic acid group and thus can be moreeffective in maintaining the low pH environment required to keep the pHindicator colorant in its dry acidic state. These alkyl phosphate freeacids have been found to be particularly effective in preserving the drystate color of the bromocresol green colorant from premature activationas caused by high humidities or destabilizing materials and/or chemicalspresent in new diaper designs. Particularly effective alkyl phosphatefree acids are stearyl phosphate free acid, cetyl phosphate free acid,and cetearyl phosphate free acids. Thus, the phosphate is a suitablystrong acid to maintain the pH indicator colorant in its acidic drystate form, and the lipophilic alkyl moiety aids in increasing itssolubility within the wetness indicator composition. In addition, thesurfactant nature of the alkyl phosphate free acids can aid in speedingup the kinetics of the color change after the wetness indicatorcomposition is contacted by urine.

Other acidic stabilizers which are particularly effective in stabilizingthe wetness indicator formula to high humidities and/or destabilizingcomponents within the diaper include, but are not limited to: organicacids, such as, but not limited to, fatty acids such as stearic acid,palmitic acid, lower molecular weight acids such as citric acid, malicacid, maleic acid, lactic acid, glycolic acid, gluconic acid, fumaricacid, adipic acid, ascorbic acid, and salicylic acid; acid esters, suchas, citrate esters, e.g., monostearyl citrate and monocetyl citrate,glycolate esters, lactate esters; phosphorus containing organic acids,such as, monostearyl phosphate and monocetyl phosphates; ethercarboxylic acids; N-acyl sarcosinic acids; N-acyl glutamic acids; N-acylethylenediaminetriacetic acid; alkane sulfonic acids; alpha-olefinsulfonic acids; alpha-sulfonic acid fatty acid methyl esters; sulfateesters; inorganic acids, such as, phosphoric acid; and combinationsthereof. Examples of suitable basic stabilizers include, but are notlimited to: monoethanolamine; diethanolamine; triethanolamine;dipropylenetriamine; diiosopropyl amine; organic diamines, such as, butnot limited to, 1,3-bis(methylamine)-cyclohexane, 1,3-pentanediamine;inorganic bases, such as, but not limited to, sodium hydroxide,magnesium hydroxide, and combinations thereof.

The stabilizer, when present is typically employed in compositions atlevels which are effective at stabilizing the colorant, from about0.001% to about 30%, from about 0.1% to about 15%, and also from about1% to about 10%, by weight of the composition.

Optional Additional Ingredients

In one optional embodiment of the present invention, the wetnessindicator composition may include optional ingredients, including, butnot limited to, surfactants, structural adjuncts, and combinationsthereof. The optional additional ingredients, when present, aretypically employed in compositions at levels which are effective atproviding the benefits of the optional additional ingredient oringredients, including from about 0.001% to about 50%, from about 0.1%to about 40%, and from about 1% to about 35%, by weight of thecomposition. The optional ingredients and amounts disclosed in U.S. Pat.No. 6,904,865, issued Jun. 14, 2005 to Klofta, et al may be used in thewetness indicator compositions of the present inventions.

Substrate

In one embodiment of the present invention, the wetness indicatorcomposition of the present invention may be on and/or in a substrate.When present on a substrate, the wetness indicator composition willtypically be placed on and/or in a substrate where the substrate will becontacted by a liquid, such as water, urine, menses, blood and the like.The substrate may include, but is not limited to, woven fabrics,nonwoven fabrics, films, sponges, and combinations thereof. Thesubstrate may comprise synthetic and/or natural materials. In oneembodiment of the present invention the optional substrate may be anarticle in its own right, such as, a continuous nonwoven fabric. Inanother embodiment of the present invention the substrate to which thewetness indicator may be applied or otherwise affixed comprises any one,or a combination of, structural components of an absorbent article,including, but not limited to, the backsheet, topsheet, fasteners,absorbent material, etc., or may be a separate element added or appliedto the product. In one optional embodiment of the present invention thewetness indicator composition is applied to the absorbent article as awhole.

The manufacture of substrates, absorbent articles and structuralcomponents thereof, for use herein form no part of this invention. Thefollowing discussion is for convenience of formulation, but is notintended to limit the type of substrate used herein.

In one embodiment of the present invention the disposable absorbentarticle is a disposable diaper. Typically, modern disposable diaperscomprise a liquid pervious topsheet a liquid impervious backsheet; anabsorbent core which may be positioned between at least a portion of thetopsheet and the backsheet; side panels; elasticized leg cuffs; anelastic waist feature; and a fastening system. In one embodimentopposing sides of the disposable diaper may be seamed or welded to forma pant. This allows the article to be used as a pull-on type diaper,such as a training pant. Additional illustrative, but non-limiting,information on construction, assembly, and the various components(including backsheets, dusting layers, upper and lower covering sheets,and webs) of disposable diapers may be found in U.S. Pat. No. 3,860,003to Buell; U.S. Pat. No. 5,151,092 to Buell; U.S. Pat. No. 5,221,274 toBuell; U.S. Pat. No. 5,554,145 to Roe et al. on Sep. 10, 1996; U.S. Pat.No. 5,569,234 to Buell et al.; U.S. Pat. No. 5,580,411 to Nease et al.;U.S. Pat. No. 6,004,306 to Robles et al.; U.S. Pat. No. 5,938,648 toLaVon et al.; U.S. Pat. No. 5,865,823 to Curro; U.S. Pat. No. 5,571,096to Dobrin et al.; U.S. Pat. No. 5,518,801 to Chappell, et al.; U.S. Pat.No. 4,573,986 to Minetola et al.; U.S. Pat. No. 3,929,135, to Thompson;U.S. Pat. No. 4,463,045 to Ahr, et al.; U.S. Pat. No. 4,609,518 to Curroet al.; U.S. Pat. No. 4,629,643 to Curro et al.; U.S. Pat. No. 5,037,416to Allen et al.; U.S. Pat. No. 5,269,775 to Freeland et al.; U.S. Pat.No. 4,610,678 to Weisman et al.; U.S. Pat. No. 4,673,402 to Weisman etal.; U.S. Pat. No. 4,888,231 to Angstadt; U.S. Pat. No. 5,342,338 toRoe; U.S. Pat. No. 5,260,345 to DesMarais et al.; U.S. Pat. No.5,026,364 to Robertson; U.S. Pat. No. 3,848,594 to Buell; U.S. Pat. No.4,846,815 to Scripps; U.S. Pat. No. 4,946,527 to Battrell; U.S. Pat. No.4,963,140 to Robertson et al.; U.S. Pat. No. 4,699,622 to Toussant etal.; U.S. Pat. No. 5,591,152 to Buell et al.; U.S. Pat. No. 4,938,753 toVan Gompel, et al.; U.S. Pat. No. 5,669,897 to LaVon, et al.; U.S. Pat.No. 4,808,178 to Aziz et al.; U.S. Pat. No. 4,909,803 to Aziz et al.:U.S. Pat. No. 4,695,278 to Lawson and U.S. Pat. No. 4,795,454 issued toDragoo; and U.S. Ser. No. 10/770,043 to LaVon; U.S. Pat. Nos. 7,318,820to LaVon et al.; 6,962,578 to LaVon; 7,377,914 to LaVon; U.S. Ser. Nos.11/715,976 to LaVon; 10/880,128 to LaVon; 11/131,799 to LaVon et al.,11/133,818 to LaVon et al.; 11/135,689 to LaVon; 11/140,888 to LaVon etal.; 11/158,563 to LaVon et al.; 11/159,916 to LaVon et al., 11/197,197to LaVon et al.; 11/210,345 to LaVon et al.; 11/224,462 to LaVon et al.;11/231,511 to LaVon et al.; 11/231,512 to LaVon et al.; 11/231,500 toLaVon et al.; U.S. Pat. No. 7,320,684 to LaVon et al.; U.S. Ser. Nos.11/286,934 to LaVon et al.; 11/286,614 to LaVon; 11/286,612 to LaVon;11/700,585 to LaVon et al.; 11/709,500 to LaVon et al.; 11/713,906 toLaVon et al.; 11/728,127 to LaVon et al.; 61/073,154 to LaVon; and61/073,169 to LaVon; US Pub. Nos. 2004/0162536 to Becker filed on Feb.11, 2004; 2007/0167928 to Becker filed on Mar. 13, 2007; 2007/0179464 toBecker filed on Mar. 13, 2007; 2007/0156108 to Becker filed on Mar. 13,2007; and 2004/0167486 to Busam filed on Feb. 11, 2004; U.S. Ser. Nos.60/936,102 to Hundorf filed on Jun. 18, 2007; 60/936,109 to Hundorffiled on Jun. 18, 2007; 60/936,149 to Hundorf filed on Jun. 18, 2007;60/936,085 to Ashton filed on Jun. 18, 2007; 60/936,084 to Ashton filedon Jun. 18, 2007; 60/936,150 to Ashton filed on Jun. 18, 2007;60/936,146 to Ashton filed on Jun. 18, 2007; 60/936,037 to Ashton filedon Jun. 18, 2007; and 61/091,799 to Hundorf filed on Aug. 26, 2008.

In one alternative embodiment of the present invention a portion of theabsorbent article, such as part or all of the topsheet, part or all ofthe barrier leg cuffs and the like, may be optionally coated with alotion, as is known in the art. Examples of suitable lotions include,but are not limited to, those described in U.S. Pat. No. 5,607,760 toRoe on; U.S. Pat. No. 5,609,587 to Roe; U.S. Pat. No. 5,635,191 to Roeet al.; U.S. Pat. No. 5,643,588 to Roe et al.; and U.S. Pat. No.5,968,025 to Roe et al.

The wetness indicator may be applied to a substrate via any means ofliquid or semi-liquid application as known in the art, including, butnot limited to, slot coating, spraying, gravure printing, ink jetprinting, and digital printing. Alternatively, the wetness indicator maybe a solid or semi-solid material affixed to a substrate via adhesivebonding, chemical bonding or intermolecular force bonding. Multipleindicators may be applied to the same substrate in overlapping ornon-overlapping geometries. The solidification process may beaccelerated via the use of convective mass transport, if evaporation ofa solvent is required, or convective or conductive heat transfer, e.g.,cooling via air or chilled rolls, etc.

As briefly described in the Background of the Invention above, thewetness indicator composition should not only adhere to the substrate(e.g., backsheet) to which it initially applied, but the wetnessindicator composition should adhere to the substrate (e.g., the dustinglayer) it faces that is inboard of the wetness indicator to ensurewicking of fluid (e.g., urine) to the wetness indicator compositionafter a wetness event. That is, when a gap exists between the wetnessindicator composition and the inboard substrate (e.g., the dustinglayer) that it faces, fluid may not travel from the absorbent core tothe wetness indicator within the desired time to signal a wetness event.

It may additionally be desired that there is substantialcontact/adherence to the substrate it faces to ensure that the wetnessindicator composition is evenly (top to bottom and side to side) wettedand thus provides the full signal intended. This can be accomplished byproviding a wetness indicator composition that has an optimized “opentime” such it is tacky enough for a long enough time to adhere to thesubstrate, but not so long that it bleeds through the substrate.

Bleeding through becomes a larger issue when the substrate is a lowerbasis weight and/or breathable film or nonwoven. Absorbent articles ofthe present invention may use backsheets having a basis weight less thanabout 60 gsm, less than about 40 gsm, or less than about 20 gsm. Saidbacksheets may be breathable, having water vapor transmission rates(according to ASTM E-96/E-96M-05) greater than about 100 g/m²/24 hr(grams of water vapor per square meter per 24 hour period), greater thanabout 1000 g/m²/24 hr, or greater than about 5000 g/m²/24 hr. Thebacksheets of the present invention may be a single layer or may be alaminate and may comprise polypropylene and/or polyethylene.

Further, nonwoven dusting layers (as well as, intermediary layersbetween the wetness indicator composition and the dusting layer) of thepresent invention may have a mean flow pore (according to ASTM F316-86)size of greater than about 1 micron, greater than about 10 micron, orgreater than about 100 microns. And may have a hydrohead value ofgreater than about 1 mm of water, greater than about 10 mm of water, orgreater than about 100 mm of water as measured by AATCC 127-1985 titled“Rising Column Strike Through.” And, nonwovens and intermediary layersmay have a basis weight of less than about 50 g/m², less than about 30g/m², or less than about 15 g/m². Nonwovens and intermediary layers ofthe present invention may comprise fibers having a diameter of less thanabout 200 microns, less than about 20 microns, or less than about 2microns. And, the fibers may be shaped (i.e., having a non-roundcross-section), including multilobal (e.g., bilobal, trilobal fibers,etc.).

In embodiments where the wetness indicator composition is in directcontact with the outboard face (outer face) of the dusting layer, thedusting layer may have a complex of thermoplastic adhesive material andabsorbent polymer material adhered to the inboard face (inner face) ofthe dusting layer. In such an embodiment, the area of the inner face ofthe dusting layer directly opposite the outer face of the dusting layerthat is adhered to the wetness indicator composition (i.e., the area theinner face of the dusting layer directly across from the wetnessindicator composition) may be from about 0.01 cm² to about 200 cm², fromabout 1 cm² to about 50 cm2, or from about 3 cm² to about 20 cm². And,the amount of the complex of thermoplastic adhesive material andabsorbent polymer material adhered to inner face of the dusting layer inthe area the inner face of the dusting layer directly across from thewetness indicator composition may be from about 1 g/m² to about 300g/m², from about 10 g/m² to about 200 g/m², or from about 25 g/m² toabout 150 g/m². This is the complex of thermoplastic adhesive materialand absorbent polymer material largely responsible for prematurelychanging the color of the wetness indicator composition.

Wetness indicator compositions that may be used with the lower basisweight and/or breathable films and nonwovens above may comprisesstraight chain alkyl moieties (which is correlated with “open time”)having a chain length from about C12 to about C300, from about C14 toabout C100, or from about C16 to about C50. Further, wetness indicatorcompositions of the present inventions may have a basis weight greaterthan about 10 g/m², greater than about 20 g/m², or greater about 25g/m². Further more, wetness indicator compositions of the presentinvention may, according to the Wetness Indicator Sample Test(Phosphate) (according to ASTM D-809) below, have a phosphorous contentof 10.0% or less, of 1.0% or less, or of 0.1% or less. And wetnessindicator compositions of the present invention may, according to theWetness Indicator Sample Test (Nitrogen) (according to ASTM D-3228(2008)) below, have a nitrogen content of 3.0% or less, of 0.3% or less,or of 0.03% or less.

In one embodiment, the wetness indicator composition may initially beapplied to an inboard face (i.e., the inner face, relative to thewearer) of the backsheet such that it adheres to the backsheet. Then theoutboard face (i.e., the outer face, relative to the wearer) dustinglayer comes in contact with wetness indicator composition such that itadheres to the dusting layer over the entire (or substantially entire)inboard surface of the wetness indicator composition.

The wetness indicator composition when present on a substrate mayprovide for a signal visible from outside the substrate, while theproduct is being worn, e.g., visible to the wearer, a caregiver, parentand the like. That is, the wetness indicator compositions are affixed tothe substrate at a portion which enables it to be in fluid communicationwith the liquid, e.g., urine, menses, blood and the like, and allows thechange initial color state to its final color state to visible to anobserver. For example, color or contrast change, is visible through thesubstrate and/or the absorbent article, such as, the of backsheet orgarment-facing covering of a disposable diaper article, which is also influid communication with the liquid, such as urine menses, blood and thelike, deposited in the absorbent core of the substrate and/or theabsorbent article.

In one optional embodiment of the present invention, the change of thecolorant from its initial color state to its final color state isvisible within a short time after the wetness indicator composition iscontacted with a liquid, e.g., urine, menses, blood and the like. In onealternative embodiment of the present invention, the change of thecolorant from its initial color state to its final color state isvisible within about 15 minutes, or within about 5 minutes after aliquid, such as urine, menses, blood and the like, contacts the wetnessindicator composition.

In another optional embodiments of the present invention, the substrate,or absorbent article comprising the substrate may be designed to allowliquid, such as urine, menses, blood, and the like, to contact thewetness indicator composition in certain regions of the substrate, orabsorbent article at various loading levels. For example, a disposablediaper may be designed to allow urine to contact the wetness indicatorcomposition located in the crotch region of the product on the firsturination, but contact the wetness indicator composition in otherregions of the disposable diaper only after the amount of urine in thedisposable diaper reaches a predetermined threshold value. For example,the absorbent core of the disposable diaper may have limited ability todistribute urine from a given region of the disposable diaper until itcontains sufficient urine to change the colorant in a wetness indicatorfrom its initial color state to its final color state in this region,thereby preventing change of the wetness indicator composition inadjacent regions of the article until the overall urine loading in thedisposable diaper increases above a given level. As the total urineloading in the disposable diaper increases, more regions of thedisposable diaper will contain sufficient urine to change the colorantin a wetness indicator that may be located in those regions from itsinitial color state to its final color state.

The wetness indicator compositions may be present on a substrate in anydesired pattern or configuration, including, but not limited to,stripes, dots, geometric shapes, irregular shapes, alphanumericcharacters, pictorial representation of animals, pictorialrepresentation of inanimate objects, cartoon characters, anthropomorphicimages, logos, trademarks and any combination or arrangement thereof.The wetness indicating compositions may be applied in any pattern or inconjunction with permanent graphics, such as, permanent graphics on theouter surfaces of a disposable absorbent article.

In one embodiment of the present invention, the wetness indicatorcompositions, when present on a substrate, is typically employed atlevels which are effective at providing visible signals, including fromabout 1 g per square meter (gsm) to about 100 gsm, from about 5 gsm toabout 75 gsm, and from about 10 gsm to about 60 gsm. However, it is tobe understood that the amount of wetness indicator present on asubstrate will depend upon many factors, such as but not limited to,substrate type (e.g., thick, thin, opacity, bulky, dense, other physicalproperties etc.), substrate material, intended use of the substrate(e.g. disposable diaper, panty liner, bandage etc.), method used forapplying the wetness indicator compositions, desired intensity of signalin either dry or after contacting liquid, desired kinetics for the colorchange, desired stability of the color within the wetness indicatorcomposition, desired pattern or configuration of the wetness indicatorcomposition on substrate, and combinations thereof.

Additional information on incorporation of wetness indicatingcompositions in and/or on substrates and/or disposable absorbentarticles can be found disclosed in U.S. Pat. No. 4,022,211 issued, onMay 10, 1977, to Timmons; U.S. Pat. No. 6,297,42, issued on Oct. 2,2001, to Olson; U.S. Pat. No. 6,307,119 issued on Oct. 23, 2001 toCammarota; and U.S. Patent Applications Nos. 20020007162A1 entitled“Absorbent articles having wetness indicating graphics incorporating atraining zone,” filed on Aug. 13, 2001, published Jan. 17, 2002, in thename of Cammarota; and 20010053898A1 entitled “Absorbent articles havingwetness indicating graphics providing an interactive training aid” filedon Jul. 24, 2001, published Dec. 20, 2001, in the name of Olson; and WO00/76438 published on Dec. 21, 2000, and assigned to Kimberly-ClarkWorldwide Inc., and WO 00/76443 published on Dec. 21, 2000, and assignedto Kimberly-Clark Worldwide Inc.

TEST METHODS

A. Controlled Temperature and Humidity (CTH) Stability Test Method:

Wetness indicators, according to this method, are first made by heatingup the wetness indicator composition about 10° C. above its meltingpoint. For the compositions in the Examples A-H below, this temperatureis in the range of about 95° C. to about 105° C. At this sametemperature, a stainless steel bird applicator (Gardco Model NumberAP-6X002ts or equivalent, Gardco Incorporated, Pompano Beach, Fla.) witha width of 4″ to 6″ and a gap of 0.002″ is also heated. On a flat andlevel lab bench is placed a series of up to 10 polypropylene backsheetfilms with a basis weight of approximately 18 gsm with dimensions ofaround 3″ by 8″. These 10 backsheet films are separated by about 2″ fromone another and each is taped to the lab bench with transparent taperunning across the top most edge of each film.

After taping the backsheet films to the lab bench, insulated gloves areplaced on one's hands and used to remove the hot wetness indicatorcomposition from the oven and place it in the vicinity near the top mostedge of the backsheet film. The hot bird applicator is also removed fromthe oven and placed near the top most edge of the backsheet with itslong dimension running parallel to the short 3″ dimension of thebacksheet film and its legs resting firmly on the lab bench rather thanon the backsheet film itself. Next, the hot wetness indicatorcomposition is dispensed along the front edge of the bird applicator andwhile firmly holding the left and right legs of the bird applicator withdownward pressure, one firmly moves the bird applicator in the directionof the long dimension of the backsheet film while maintaining the birdapplicator's long dimension parallel to the short width dimension of thebacksheet film.

One can vary the basis weight of the wetness indicators applied to thebacksheet by changing the viscosity of the wetness indicatorcomposition, by applying the composition at different temperatures, bychanging the speed at which the bird applicator is dragged across thebacksheet film, or by varying the gap of the bird applicator.

The basis weight of the wetness indicator composition applied to thebacksheet film can be calculated by cutting out the wetness indicator ofknown dimensions and weighing it on a balance. The basis weight of thewetness indicator composition and backsheet film combination iscalculated by dividing the weight of the backsheet film in units ofgrams by its area using the units of m². The basis weight unit of gramsper square meters is typically abbreviated as gsm or g/m². To calculatethe basis weight of the wetness indicator applied to the backsheet film,one must then subtract the basis weight of the backsheet film from thebasis weight calculated for the wetness indicator composition applied tothe backsheet film.

For the wetness indicators prepared in this manner, one can typicallyprepare a variety of wetness indicator basis weights ranging from 10 gsmto 100 gsm. As noted, these range of basis weights can be made byvarying the speed at the which the bird applicator is dragged across thebacksheet film, changing the temperature of the composition, using adifferent gap setting for the applicator, or altering the othervariables mentioned above.

After the wetness indicators are prepared and the basis weightscalculated, they are applied to the dusting layer of a substantiallycellulose free core by firmly pressing them onto the core with thewetness indicator side in direct contact with the dusting layer of thesubstantially cellulose free core. The wetness indicators can be firmlyapplied to the dusting layer using a roller made with a hard plastic orwood material. Typically, one tries to apply a variety of basis weightwetness indicators to the dusting layer side of the core in order tostudy the effect of basis weight on such properties like stability,kinetics, and colorant retention.

After the wetness indicators have been applied to the dusting layer ofthe substantially cellulose free core, they are placed dusting layerside up in a controlled temperature and humidity room which iscontrolled to a humidity of 75% and a temperature of 40° C. The time anddate at which the wetness indicators are placed in the room is recorded,and the samples are periodically checked for any premature colorchanging activity. For bromocresol green containing compositions, suchas Examples A-H, the initial and stable dry state color is yellow. Anycolor change observed for these bromocresol green containingcompositions wetness indicator compositions using digital photographyand by use of the following 6-point scale of 0 to 5:

-   -   “0” corresponds to no color change of the wetness indicator        through the backsheet film remaining, such that the wetness        indicator remains completely yellow over the backsheet film area        corresponding to the wetness indicator area;    -   “1” corresponds to the presence of green or blue regions over        less than 10% of the backsheet film area corresponding to the        wetness indicator area;    -   “2” corresponds to the presence of green or blue regions over        10% to 40% of the backsheet film area corresponding to the        wetness indicator area;    -   “3” corresponds to the presence of green or blue regions over        41% to 60% of the backsheet film area corresponding to the        wetness indicator area;    -   “4” corresponds to the presence of green or blue regions over        61% to 90% of the backsheet film area corresponding to the        wetness indicator area; and    -   “5” corresponds to the presence of green or blue regions over        greater than 90% of the backsheet film area corresponding to the        wetness indicator area.        The wetness indicators, through the backsheet films, are        photographed or graded in this manner for storage up to 12        months in this or other controlled temperature and humidity        rooms.        B. Colorant Kinetics Test Method:

After the wetness indicators are made (they are in the form of a film)and applied to the substantially cellulose free cores as described abovein the CTH stability test, the diapers the wetness indicators have beenincorporated into can be tested to determine how quickly the wetnessindicators change from their stabilized dry state color to their wetstate color after synthetic urine contacts the wetness indicator film.For wetness indicators with wetness indicator compositions containingonly bromocresol green, the dry state color is yellow and the wet statecolor is blue. The wetness indicators applied to the dusting layer ofthe substantially cellulose free core should approximately mimic boththe basis weight and dimensions of the wetness indicators that would bemarketed to consumers. Thus, a basis weight of 20 gsm to 60 gsm would bemost appropriate with dimensions of approximately 5 millimeters in widthby 160 milliliters in length. This wetness indicator should be appliedto the dusting layer such that is its long dimension is parallel to thelong dimension of the diaper. And, it should also be applied on theoutside face of the dusting layer such that it runs along the center ofthe core of the diaper.

First, the diaper comprising the wetness indicator is placed with thewetness indicator side down (topsheet side up) on a clear, transparent,and colorless piece of polycarbonate with dimensions approximating 14″long by 6″ wide by 0.25″ thick. This polycarbonate sheet on which thediaper sits is then supported on both ends with legs to which a mirroris attached. The mirror is angled at 45 degrees and sits directly belowthe sample so one can view the wetness indicator side of the diaperduring this colorant kinetics test.

Another clear, transparent, and colorless polycarbonate sheet is thenplaced on the topsheet side of the diaper. A round hole of 1 inch indiameter is cut into this polycarbonate sheet with its center located inthe middle of the 6 inch width dimension and 5 inches from one of theedges in the 14 inch long dimension. Onto this hole, a 3 inch long andclear, transparent polycarbonate cylinder is attached which has a roundhole diameter of 1 inch (which is made to overlap the 1 inch round holein the polycarbonate sheet) and a wall thickness of 0.25 inches.

This top polycarbonate sheet is placed on top of the diaper so thecenter of the polycarbonate cylinder sits on top of the core in alocation designed to accept the initial urination event. After placingthis polycarbonate sheet on the diaper, two 6.5 pound weights are placedon either end of the sheet in order to mimic the weight of the baby ontop of the diaper.

Synthetic urine is then prepared according to the following recipe asdisclosed in U.S. Pat. No. 6,772,708 to Klofta. The synthetic urine isthen heated to a temperature of 38° C. in order to mimic bodytemperature of urine. 40 milliliters of this heated synthetic urine isthen measured into a graduated cylinder. This 40 milliliters of thesynthetic urine is then poured into the polycarbonate cylinder on top ofthe diaper at a rate of approximately 2 to 3 milliliters per second.After all of synthetic urine is poured into the cylinder, a stop watchis started. An additional forty milliliters is poured into the cylinderat a rate of approximately 2 to 3 milliliters per second at both the 5and 10 minute time points as measured using the stop watch.

The color of the wetness indicator is then monitored (as can be seenthrough the backsheet) at the following time points after the stop watchis started after the first 40 milliliter volume of synthetic urine ispoured into the cylinder: 1) 2 minutes and 2) 5 minutes. After thesecond dose of 40 milliliters of synthetic urine is added at the 5minute point, observations are recorded at the 10 minute point, andafter the third dosed of 40 milliliters is added at the 10 minute point,final observations are recorded at the 15 minute point. The color can bemeasured using the following 6-point scale of 0 to 5:

-   -   0 denotes no color change of the wetness indicator through the        backsheet film remaining in its dry state color, such that the        wetness indicator remains completely yellow over the backsheet        film area corresponding to the wetness indicator area;    -   1 denotes less than 10% of the backsheet film area corresponding        to the wetness indicator area changing to the wet state color;    -   2 denotes 10-40% of the backsheet film area corresponding to the        wetness indicator area changing to the wet state color;    -   3 denotes 41-60% of the backsheet film area corresponding to the        wetness indicator area changing to the wet state color;    -   4 denotes 61-90% of the backsheet film area corresponding to the        wetness indicator area changing to the wet state color; and    -   5 denotes greater than 90% of the backsheet film area        corresponding to the wetness indicator area changing to the wet        state color.        C. Colorant Retention Test Method:

The colorant retention test is performed on the identical diaper used inthe colorant kinetic test. The diaper comprising the wetness indicatorcontinues to be sandwiched between the polycarbonate sheets described inthe colorant kinetic test method (above) and continues to be weighteddown for a total of 2 to 16 hours.

After this range of time is met, the time is recorded and the diaper isflipped over so the wetness indicator side faces up for easy viewing bythe naked eye. Both the color of the wetness indicator (as viewedthrough the backsheet), as well as the areas located next to it areinspected to determine dye retention within the wetness indicator, aswell as dye leaching into areas residing next to the wetness indicator.Even though the color could be measured spectrophotometrically, a visualgrading system can also be applied. The color of wetness indicator canbe graded according to the following scale:

-   -   0 denotes less than 10% of final wet state color residing within        the wetness indicator through the backsheet film;    -   1 denotes 10% to 50% of the final wet state color remaining        within the wetness indicator through the backsheet film    -   2 denotes 51% to 90% of the final wet state color remaining        within the wetness indicator through the backsheet film; and    -   3 denotes greater than 90% of the final wet state color        remaining within the wetness indicator through the backsheet        film.        Any colorant leaching into the surrounding areas in the vicinity        of the wetness indicator is simply recorded with a yes or no        designation. A “yes” denotes the observation of some of the wet        state color residing in the areas around the wetness indicator.        A “no” denotes the presence of no wet state color within the        surrounding areas.

EXAMPLES A-H

Component A B C D E F G H First Binding Agent¹ 33.00 33.01 32.76 32.9532.61 34.40 58.8 48.8 First Binding Agent² 15.00 15.01 14.93 15.01 14.8115.57 HLB Modifier³ 19.03 18.99 19.06 19.03 18.96 19.42 16.0 16.0Stabilizer⁴ 3.41 3.41 3.17 2.95 2.85 2.08 5.0 9.0 Stabilizer⁵ 0.20 — — —— — — — Second Binding agent⁶ 1.00 1.00 1.13 0.81 0.99 1.04 1.0 1.0Second Binding agent⁷ — — — — 1.95 2.01 3.0 3.0 Colorant⁸ 0.18 0.18 0.200.20 0.20 0.20 0.20 0.2 Colorant⁹ — — — 0.02 — — — — Surfactant¹⁰ 27.7828.01 28.44 28.52 27.37 24.98 12.0 18.0 Anti-Oxidant¹¹ 0.40 0.39 0.310.51 0.26 0.30 0.3 0.3 CTH Stability Test (5 0 1 1 1 2 3 4 3 days at 75%Relative Humidity & 40° C.) Colorant Kinetics Test 4 4 4 4 4 4 3 3 (at 5minutes) Colorant Retention Test 2 2 2 2 3 3 4 4 (at 4 hours) WetnessIndicator 0.33 0.33 0.31 0.28 0.27 0.20 0.48 0.87 Sample Test(Phosphate)(%) Wetness Indicator 320 320 360 260 840 870 1120 1120Sample Test (Nitrogen) (parts per million) ¹Pentaerythritol Rosin Ester,(Sylvatac RE 98 from Arizona Chemical, Jacksonville, FL) ²PolymerizedRosin (Sylvaros PR-295 from Arizona Chemical, Jacksonville, FL) ³W835Microcrystalline Wax from Crompton, Petrolia, PA) ⁴Cetyl Phosphate FreeAcid (Hostaphat CC-100 from Clariant) ⁵Anhydrous Citric Acid, (EMD)⁶Cocoalkylmethyl[ethoxylated(15)] ammonium chloride (Ethoquad C/25) fromAkzo Incorporated, Chicago, IL). ⁷Dimethyl(2-ethylhexylhydrogenatedtallowalkyl)ammonium methyl sulfate, (HTL8(W)-MS) from AkzoIncorporated, Chicago, IL) ⁸Bromocresol Green, Free Acid from CurtissLabs, Bensalem, PA ⁹D&C Red #17 (Sensient Inc.) ¹⁰C₂₀-C₄₀ Pareth-10(Performathox 450 from New Phase Incorporated, Sugar Land, TX) ¹¹Irganox1010FF from Ciba,

Each of the Examples A-H are made by mixing the HLB modifier andviscosity modifier and heating the mixture at 100° C. until completelymelted. Reduce the heat on this HLB/Viscosity modifier premix to 95° C.and maintain mixing. In another clean, glass container, mix the firstbinding agent, stabilizer, and the surfactant. Heat and stir thismixture at 90° C. until completely melted. Add in the HLB/Viscositymodifier premix to the mixture of first bindingagent/stabilizer/surfactant and heat and mix at 90° C. Add to thismixture the second binding agent and mix until the temperature reaches90° C. Finally, add to this mixture the colorant and mix forapproximately 1 hour at 90° C. until the mixture is clear, transparentand light orange in color.

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. An absorbent article comprising: a backsheet; acore comprising less than 1% by weight cellulosic fibers; a wetnessindicator composition comprising a stabilizer, a colorant, and a matrix;and wherein a wetness indicator sample comprises phosphate, and,according to the Wetness Indicator Sample Test (Phosphate), has aphosphate content of 10% or less.
 2. The absorbent article of claim 1,wherein the wetness indicator composition comprises materials selectedfrom the group consisting of cationic clay materials, quaternaryammonium compounds, ethoxylated quaternary ammonium compounds,quarternized silicone compounds, cationic guars, cationic exchangeresins, anionic exchange resins, polyacrylic acid polymers, organicacids, and combinations thereof.
 3. The absorbent article of claim 1,wherein the wetness indicator composition comprises an amine and/or aquaternary ammonium salt.
 4. The absorbent article of claim 1, whereinthe stabilizer is acidic.
 5. The absorbent article of claim 4, whereinthe acidic stabilizer is selected from the group consisting of stearicacid, palmitic acid, citric acid, salicylic acid, monostearyl citrate,monocetyl citrate, monostearyl phosphate, distearyl phosphate, monocetylphosphate, dicetyl phosphate, monocetearyl phosphate, dicetearylphosphate, ether carboxylic acid, N-acyl sarcosinic acid, N-acylglutamic acid, N-acyl ethylenediaminetriacetic acid, alkane sulfonicacid, ethoxylated alkane sulfonic acid, alpha-olefin sulfonic acid,alpha-sulfonic acid phosphoric acid, alkane sulfate acids, ethoxylatedalkane sulfate acids, and combinations thereof.
 6. The absorbent articleof claim 1, wherein the stabilizer is an alkyl phosphate free acid. 7.The absorbent article of claim 1, wherein the wetness indicatorcomposition comprises straight chain alkyl moieties having a chainlength from about C12 to about C300.
 8. The absorbent article of claim1, wherein the colorant is a pH indicator.
 9. The absorbent article ofclaim 1, wherein the colorant is selected from the group consisting ofbromocresol green, bromocresol purple, bromophenol blue, m-cresolpurple, cresol red, chlorophenol red, bromothymol blue, bromopyrogallolred, bromoxylenol blue, acridine, acridine orange, oil soluble dyes, andcombinations thereof.
 10. The absorbent article of claim 1, wherein thematrix is acidic.
 11. The absorbent article of claim 1, wherein thematrix comprises a binder having a rosin selected from the groupconsisting of rosins, rosin esters, pentaerythritol rosin ester, andpolymerized rosins.
 12. The absorbent article of claim 1, wherein thewetness indicator composition further comprises one or more selectedfrom the group consisting of an HLB modifier, a surfactant, ananti-oxidant, and combinations thereof.
 13. The absorbent article ofclaim 1, comprising a surfactant selected from the group consisting ofnonionic surfactants, anionic surfactants, cationic surfactants,amphoteric surfactants, and combinations thereof.
 14. The absorbentarticle of claim 1, comprising a structural adjunct selected from thegroup consisting of HLB modifiers, viscosity modifiers, hardeningagents, and combinations thereof.
 15. The absorbent article of claim 1,wherein the wetness indicator is affixed to the article in one or morepatterns selected from the group consisting of stripes, dots, geometricshapes, irregular shapes, alphanumeric characters, anthropomorphicimages, pictorial representation of animals, pictorial representation ofinanimate objects, cartoon characters, logos, trademarks andcombinations thereof.
 16. The absorbent article of claim 1, furthercomprising a dusting layer, wherein the dusting layer is surfactantfree.
 17. An absorbent article comprising: a backsheet; a corecomprising less than 1% by weight cellulosic fibers; a wetness indicatorcomposition comprising a stabilizer, a colorant, and a matrix; andwherein a wetness indicator sample comprises nitrogen, and, according tothe Wetness Indicator Sample Test (Nitrogen), has a nitrogen content of3% or less.
 18. The absorbent article of claim 17, wherein the wetnessindicator composition comprises an amine and/or a quaternary ammoniumsalt.
 19. The absorbent article of claim 18, wherein the stabilizer isan alkyl phosphate free acid.
 20. The absorbent article of claim 19,wherein the wetness indicator composition comprises straight chain alkylmoieties having a chain length from about C12 to about C300.
 21. Theabsorbent article of claim 17, wherein the wetness indicator compositioncomprises straight chain alkyl moieties having a chain length from aboutC14 to about C100.
 22. The absorbent article of claim 17, wherein thewetness indicator composition comprises straight chain alkyl moietieshaving a chain length from about C16 to about C50.
 23. The absorbentarticle of claim 17, wherein the wetness indicator sample, according tothe Wetness Indicator Sample Test (Nitrogen), has a nitrogen content of0.3% or less.
 24. The absorbent article of claim 21, wherein the wetnessindicator sample, according to the Wetness Indicator Sample Test(Nitrogen), has a nitrogen content of 0.03% or less.